On 30.03.2016 18:36, Laurent Vivier wrote:
> setup_frame()/setup_rt_frame()/restore_user_regs() are using
> MSR_LE as the similar kernel functions do: as a bitmask.
>
> But in QEMU, MSR_LE is a bit position, so change this
> accordingly.
>
> The previous code was doing nothing as MSR_LE is 0,
> and "env->msr &= ~MSR_LE" doesn't change the value of msr.
>
> And yes, a user process can change its endianness,
> see linux kernel commit:
>
> fab5db9 [PATCH] powerpc: Implement support for setting little-endian mode
> via prctl
>
> and prctl(2): PR_SET_ENDIAN, PR_GET_ENDIAN
>
> Signed-off-by: Laurent Vivier <laur...@vivier.eu>
> ---
> linux-user/signal.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/linux-user/signal.c b/linux-user/signal.c
> index a233bab..f1b597b 100644
> --- a/linux-user/signal.c
> +++ b/linux-user/signal.c
> @@ -4588,7 +4588,7 @@ static void restore_user_regs(CPUPPCState *env,
>
> /* If doing signal return, restore the previous little-endian mode. */
> if (sig)
> - env->msr = (env->msr & ~MSR_LE) | (msr & MSR_LE);
> + env->msr = (env->msr & ~(1ull << MSR_LE)) | (msr & (1ull << MSR_LE));
>
> /* Restore Altivec registers if necessary. */
> if (env->insns_flags & PPC_ALTIVEC) {
> @@ -4703,7 +4703,7 @@ static void setup_frame(int sig, struct
> target_sigaction *ka,
> #endif
>
> /* Signal handlers are entered in big-endian mode. */
> - env->msr &= ~MSR_LE;
> + env->msr &= ~(1ull << MSR_LE);
>
> unlock_user_struct(frame, frame_addr, 1);
> return;
> @@ -4798,7 +4798,7 @@ static void setup_rt_frame(int sig, struct
> target_sigaction *ka,
> #endif
>
> /* Signal handlers are entered in big-endian mode. */
> - env->msr &= ~MSR_LE;
> + env->msr &= ~(1ull << MSR_LE);
>
> unlock_user_struct(rt_sf, rt_sf_addr, 1);
> return;
>
Reviewed-by: Thomas Huth <h...@tuxfamily.org>
